Trailers adapted to be towed behind a vehicle conventionally include a frame on which is mounted ground engaging wheels and a trailer bed, the frame also supporting a forwardly projecting drawbar fitted with a hitch by means of which the drawbar may be coupled to a towing vehicle. There apparently is no standard height that trailer drawbars occupy above ground level, nor does there appear to be any standard height above ground level that a trailer hitch may be mounted on a towing vehicle. On the contrary, it appears that trailer hitches and drawbars are constructed and assembled with little or no regard for standardization. As a consequence, it is not uncommon for the beds of some trailers, when coupled to a towing vehicle, to be forwardly and downwardly inclined or forwardly and upwardly inclined depending upon whether the vehicle mounted trailer hitch is relatively low or relatively high above ground level. Such non-horizontal positions of a trailer bed are undesirable since articles supported on a downwardly pitched trailer bed will tend to move forwardly when the trailer is decelerated and at a rate greater than would be the case if the trailer bed were horizontal. In addition, the vertical motion to which the trailer is subjected because of unevenness in road surfaces causes the contents of a forwardly pitched trailer bed also to move forwardly.
The same objections occur with respect to a rearwardly pitched trailer frame bed, with the exception that the contents of the bed tend to move rearwardly in response to acceleration of the trailer and as a result of vertical vibrations due to road surface unevenness.
The disadvantages of towing a trailer with its bed in any position other than substantially horizontal has been recognized in the past and numerous proposals have been made for enabling the drawbar of a trailer to be adjusted so as to compensate for differences in the height at which a hitch member is mounted on a towing vehicle. Typical of the previous proposals are those disclosed in U.S. Pat. Nos. 1,190,237; 2,228,699; 2,277,900; 2,327,308; and 3,830,522. Although these previous proposals will accomplish the desired objective, they are rather cumbersome, expensive, and employ an undesirably large number of different parts. Further, none of them enables the trailer bed with which it is associated to be tilted rearwardly so that its rear end rests upon the ground to facilitate the loading or unloading of an article, such as a mobile snowmobile, on or off the trailer bed while the drawbar remains coupled to the towing vehicle.
Among the objects of the present invention is the provision of a trailer and drawbar assembly which enables a trailer bed to be maintained in a substantially horizontal position when coupled to any one of a large number of different vehicles and which enables the trailer bed to be tilted to facilitate loading and unloading of the trailer without necessitating uncoupling of the drawbar from the towing vehicle.